1. Field of the Invention
The present invention relates to a Wireless Broadband (WiBro) mobile communication system and, in particular, to a power saving method for a mobile terminal of the WiBro communication system.
2. Description of the Related Art
The technological advancements and rising usage of mobile communication have dramatically influenced people's everyday life. As a result of these technological advancements, mobile communication devices are becoming ever more popular and widely accepted for data communications as well as for conventional voice communications, and user requirements for various convenient services and high speed data transmission increase.
Wireless Broadband (WiBro) is a wireless broadband Internet technology developed for satisfying user's demands for wireless voice and data communication while on the move. WiBro provides the user with voice and data connectivity anytime and anywhere even on the move.
WiBro operates in the 2.3 GHz bandwidth and covers about 1 Km range. WiBro supports high-speed data service in an indoor and outdoor stationary and pedestrian-speed and mobile environment of below 60 Km/h. WiBro also provides high speed and reliable Internet service at a low cost relative to other communication networks.
A mobile terminal provides for transition between different modes (i.e., active, sleep, and idle modes). In the active mode, the mobile terminal transmits and receives packets to and from a base station. The sleep mode is intended to minimize power consumption of the mobile terminal by pre-negotiated periods of absence from the base station air interface. The idle mode allows the mobile terminal to become periodically available for downlink broadcast traffic so as to conserve power and operational resources.
The mobile terminal typically spends a large majority of its time in the idle and sleep modes and the power consumption during a standby mode including the idle and sleep modes has a major impact on efficient power management for the overall standby and active modes. That is, power conservation in the standby mode is an important issue for efficient power management.
Since most WiBro terminals are mobile terminals, high power consumption in the standby mode reduces the standby and communication time, resulting in reduction of user satisfaction.
FIG. 1 is a message flow diagram illustrating an operation of a conventional mobile terminal in a standby mode.
Referring to FIG. 1, if a modem 120 of the mobile phone receives a Deregistration Request message (Dreg_Req) from a host 110 of a mobile phone in step S101, the modem 120 transmits the Deregistration Request message (Dreg_Req) to a base station 130 in step S103. Upon receiving the Deregistration Request message (Dreg_Req), the base station 130 transmits a Deregistration Confirmation message (Dreg_Cmd) to the mobile phone in response to the Deregistration Request message (Dreg_Req) in step S105.
Upon receiving the Deregistration Confirmation message (Dreg_Cmd), in step S107 the modem 120 transmits a Deregistration ACKnowledgement message (Dreg_ACK) to the host 110.
If the Deregistration ACKnowledgement message (Dreg_ACK) is received, the host 110 transmits a channel state request message (Air_State_Req) to the modem 120 in step S109.
In response to the channel state request message (Air_State_Req), the modem 120 collects channel state information in step S111 and then transmits a channel state response message (Air_State_Resp) containing the collected channel state information to the host 110 in step S113. The mobile terminal checks the channel state by repeating the steps S109 to S113 in the standby mode.
As described above, the host 110 and the modem 120 of the mobile terminal are turned on in the standby mode, resulting in power consumption.
Particularly, the WiBro mobile terminal operates in different modes according to settings configured by a user or by the mobile terminal itself in a service zone. The WiBro mobile terminal checks a WiBro service availability and types of services in a current location by monitoring the channel state in the standby mode. The WiBro mobile terminal can be implemented with another network modem chip in addition to a WiBro modem chip for supporting various network services. Since most WiBro terminals are battery-powered mobile terminals, low standby power consumption is a significant factor for determining the performance of a mobile terminal.
However, since the conventional WiBro mobile terminal must maintain channel synchronization, power consumption for obtaining the channel state is required even in the standby mode. Accordingly, there can be room for further saving the power in the standby mode.